1. Field of the Invention
This invention relates to a magnetic recording and reproducing apparatus, and more particularly to a device equipped therewith for automatically opening and closing a shutter of a disc cartridge used in combination with the recording and/or reproducing apparatus along with insertion and discharge of the disc cartridge.
2. Description of the Prior Art
As a medium of magnetic or magneto optical recording and reproducing, it has recently been known a magnetic or magneto optical disc.
In the U.S. Pat. No. 4,517,617 issued to Ohkawara, there is disclosed a disc cartridge comprising a hard jacket made from such material as plastic. The recording disc is substantially enveloped within the hard jacket for preventing damage and contamination of the disc itself and/or a recording area thereof which otherwise might occur when handling the disc or inserting it into the recording and reproducing apparatus. The hard jacket is provided with an aperture for insertion of a magnetic head mounted on the recording and reproducing apparatus when installed or loaded thereon. This head insertion aperture is normally closed by a shutter member slideably connected to the hard jacket, capable of preventing dust or fingerprints from entering through the head insertion aperture and therefore preventing contamination of the recording area of the disc. The shutter is provided with an access window which will allow the magnetic head to obtain access to the recording area of the disc, when the disc cartridge is loaded into the apparatus, for performing desired recording and/or reproducing operation.
With the system and apparatus disclosed in the above-referred U.S. Pat. No. 4,517,617 the shutter must be hand-manipulated to be laterally slid or opened before the disc cartridge is loaded into the apparatus, and after completing desired recording and/or reproducing operation and then discharging the disc cartridge out of the apparatus, the shutter must be closed by the operator's hand, which is troublesome. Further, fingerprints or other foreign matter would be adhered to the recording area of the disc when manipulating the disc cartridge for opening or closing the shutter.
This problem can be solved by a mechanism or device capable of automatically opening and closing the shutter as the disc cartridge is being inserted into the apparatus and discharted out of the apparatus. A typical one of such device is disclosed in the Japanese Utility-Model Publication Sho. 62-15895, which includes an operating lever rotatably mounted on the recording and reproducing apparatus and a cut-out notch formed at one side of the front edge of the shutter. The lever has at its one end a vertical pivot connected to the apparatus and at the other end a leading end in engagement with the notch of the shutter, said one end forward a direction opposite to the cartridge loading direction and the other end forward a direction opposite to the cartridge ejecting direction. During the cartridge loading or advancing operation, the engagement between the other end of the lever and the notch will cause the shutter to automatically open. While, in turn, the cartridge is being ejected away from the loaded position in the apparatus, the lever is rotated in the opposite direction due to a spring means connected to the apparatus, as well as another spring means connected between the shutter and the hard jacket for normally biasing the shutter toward the closed position, thereby automatically closing the shutter.
In the above-referred prior art device, the lever is arranged substantially above the shutter of the disc cartridge which is full-loaded in a holder of the magnetic recording and reproducing apparatus and there is required a considerable space for installing the shutter operating mechanism above the apparatus. In another type recording and reproducing apparatus for use in combination with magneto optical disc, however, as known, it will be necessary to mount a bias magnet on the apparatus in opposition to an optical head mechanism, across the disc in the cartridge installed in the loaded position, which becomes difficult or practically impossible to install the shutter operating lever substantially above the shutter as in the same manner in the prior art device.
We have attempted that the aforementioned prior art arrangement of the shutter operating lever be modified such that the pivot is mounted relatively in the backside of the apparatus with the engaging end oriented toward the cartridge loading direction. However, realization of such arrangement has been found difficult because a relatively great angle should be provided between the lever and the cartridge in order to actuate the shutter without a hitch, and the lever has a length in a limited range which is of necessity determined in correspondence with a stroke required for opening and closing the shutter. This will be especially difficult where the notch formed in the front edge of the shutter is arranged in close vicinity to the side face of the disc cartridge, leaving only a limited space available on the apparatus for mounting the pivot of the lever arranged outwardly of the side face of the disc cartridge.